Q 11-04-140JEE MainJEE Main 2022 (26 Jun, Shift 2)Medium
A system of $10$ balls each of mass $2\ \text{kg}$ are connected via massless and unstretchable string. The system is allowed to slip over the edge of a smooth table as shown in figure. Tension on the string between the 7th and 8th ball is ______ N when the 6th ball just leaves the table.
Numerical value type. Enter your answer.
Answer: 36
When the 6th ball has just left the table, balls 1–6 hang and balls 7–10 lie on the smooth table. With $g = 10\ \text{m s}^{-2}$,
$$a = \frac{6\times2\times10}{10\times2} = 6\ \text{m s}^{-2}$$
The string between balls 7 and 8 pulls balls 8, 9 and 10 ($6\ \text{kg}$) along the table:
$$T = 6\times6 = 36\ \text{N}$$
Solution by Sreeraj P, M.Sc Physics